From 3d09fc424406b5610964507b3eb73cebbc3b4c38 Mon Sep 17 00:00:00 2001 From: Jon Paul Maloy Date: Wed, 25 Jun 2014 20:41:30 -0500 Subject: [PATCH] tipc: eliminate case of writing to freed memory In the function tipc_nodesub_notify() we call a function pointer aggregated into the object to be notified, whereafter we set the function pointer to NULL. However, in some cases the function pointed to will free the struct containing the function pointer, resulting in a write to already freed memory. This bug seems to always have been there, without causing any notable harm. In this commit we fix the problem by inverting the order of the zeroing and the function call. Signed-off-by: Jon Maloy Signed-off-by: David S. Miller --- net/tipc/node_subscr.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/tipc/node_subscr.c b/net/tipc/node_subscr.c index 7c59ab1..2d13eea 100644 --- a/net/tipc/node_subscr.c +++ b/net/tipc/node_subscr.c @@ -84,11 +84,13 @@ void tipc_nodesub_unsubscribe(struct tipc_node_subscr *node_sub) void tipc_nodesub_notify(struct list_head *nsub_list) { struct tipc_node_subscr *ns, *safe; + net_ev_handler handle_node_down; list_for_each_entry_safe(ns, safe, nsub_list, nodesub_list) { - if (ns->handle_node_down) { - ns->handle_node_down(ns->usr_handle); + handle_node_down = ns->handle_node_down; + if (handle_node_down) { ns->handle_node_down = NULL; + handle_node_down(ns->usr_handle); } } } -- 2.7.4